Process for preparing gamma-aldols and gamma-ketols



Patented Sept. 13, 1949 PROCESS FOR PREPARING y -ALDOLS AND y-KETOLSMaurice Maincon and Pierre Chassaing, Melle,

France, assignors to Les Usines de Melle (Societe Anonyme),Saint-Leger-les-Melle, France,

a company of France No Drawing. Application Mai-ch17, 1945, Serial No.583,379. In France March 17, 1944 7 Claims.

This invention relates to the manufacture of 'y-aldols and v-ketolshaving four or more carbon atoms, from compounds which possess atetrahydrofurane nucleus in their molecule.

It is already known to produce carbonyl compounds by oxidizing furane orderivatives thereof by means of oxygen or agas containing oxygen, and tosubject the resulting peroxide to decomposition or rearrangement,possibly with hydrogenation.

Our invention mainly differs from the prior method in its dealing withcompounds having a tetrahydrofurane nucleus instead of a furane nucleus.As a matter of fact, we have found that saturation of double bonds infurane by means of hydrogen results in an extraordinary enhancement ofautoxidation capacity of those compounds which possess said nucleus.Thus, for instance, the rate of oxygen absorption is 20 times largerthan in the case of above mentioned furane compounds, so that for agiven output, the size of the apparatus may be reduced. Oxidationreaction starts from 25. C. It is favoured by an increase oftemperature. Thus, for instance,

at 50 C. it is 35 times faster than at C. Metal salts commonlyv used asoxidation catalysts such as cobalt, nickel, manganese, copper and likeacetates are also found substantially to accelerate reaction; exposureto light is likewise favourable.

The peroxide thus obtained may easily be isolated from excesstetrahydrofurane compound by evaporation at a, low temperature. Bydecomposing the peroxide, there is obtained a product which has acarbonyl group and a hydroxy group in relative -position; it will beeither a 'y-ketol or a zy-aldol according to the position of thesubstituent radical or radicals with respect to the oxygen atom in theoriginal tetrahydrofurane nucleus. Tetrahydrofurane itself always yieldsan aldol.

The peroxide may be decomposed either through hydrolysis in acid oralkaline medium or through careful hydrogenation, hydrogen peroxide inthe first case and water in the second case being produced besides ketolor aldol. Still more simply it is possible to subject said peroxide to amoderately increasing temperature in order to produce its spontaneousdecomposition with evolution of oxygen in statu nascendi. As thedecomposition is exothermic, it proceeds with acceleration and in orderto keep it at a proper rate, one is led to cool after reaction hasstarted, for adjusting temperature to a constant value.

The aforesaid manner of decomposition by means of heat is particularlyadvantageous because peroxide may be decomposed pari passu;

with its formation in the very oxidation bath of the tetrahydrofuranederivative: it is only necessary to-keep the reactant mixture at atemper-- ature above40 C. Heat evolved asa consequence:

of decomposition is suflicient 'to' maintain the: temperature of thereactant mixture without any extraneous heat supply. 0n the contrary,one: often is led to cool for keeping temperature at; the proper value.The reaction product is then. distilled with a view to recoveringunaltered start-- ing material; ketol or aldol generally admixed with anamount of peroxide is obtained as residue.

The foregoing process may advantageously be 1 performed in a continuousrun, which is particuj larly advisable when Working on a commercial.

scale. To this end, one continually withdraws from the reaction vessel amixture containing unconverted tetrahydrofurane derivative which iseasily driven off by distillation, ketol or aldol and a more or lesslarge proportion of' peroxide which may be either returned to thereaction vessel, or decomposed into ketol or aldol by heating,hydrolysis or hydrogenation.

The following examples which have no limitative character will show howthis invention may be carried out.

Example 1.l00 litres of tetrahydrofurane together with 0.1 per cent of amixture of cobalt acetate and nickel acetate by equal parts was stirredat 20 C. in an atmosphere of oxygen,

fresh oxygen being blown into the vessel as ab-- sorption took place.After 10 hours, 2 cubic meters of oxygen were absorbed. Excesstetrahydrofurane was then driven off by evaporation at a.

low temperature and as a residue we obtained 9,200 g. of peroxide whichwere converted into: C.

7,800 g. of butyraldol-1z4 whenheated to 50 Example 2.-200 litres ofZ-methyltetrahydrm furane together with 0.2 per acetate were stirred atC. in an atmosphere of oxygen. After 10 hours, the amount of absorbedoxygen Was 12 cubic meters. The reaction product contained besidesexcess 2-methyltetra- 'hydrofurane, 40 kg. of acetopropyl alcohol (orpentanolone) and 21 kg. of peroxide; the latter might be hydrolyzed into13.8 kg. of acetopropyl alcohol when boiled for an hour in the presenceof a normal solution of sulphuric acid.

Example 3.300 litres of 2-methyltetrahydrofurane were placed in a vesselhaving a capacity of 400 litres and provided with heating and coolingmeans, then oxygen was introduced as required while the temperature waskept at '70 cent of manganese.

per hour of reactant liquid were withdrawn in a;

continuous manner from the bath th e y contained 6 kg. of acetopropylalcohol aiid*2'= litres"-qf methyltetrahydrofurane peroxide whichwerere-lo turned to the vessel together-with unconvertedmethyltetrahydrofurane. I v I f Example 4.In the same vesselasinfExamplez 3, operated in a continuous fashion, 250 litres of 3. Theprocess which comprises passing a gas that contains oxygen through atetrahyrofurane compound of the class consisting of tetrahydrofurane andalkyl substituted-tetrahydrqfuranes ataiternperature' of aboutyHftoabout 120 C., so as to obtain a product containing a 'y-hydroxyexpaliphatic compound; and isolating said aliphatic compound from saidproduct.

l. A continuous process which comprises maintaining a liquid body of atetrahydrofurane compound of the class consisting of tetrahydrofuraneand alkyl} substituted tetrahydrofuranes, the correspondingpeitoxide,and the corresponding 7- hydroxy oxoaliphatic compound, at a tempera-2:5-dimethyltetrahydrofurane were placed, and 5 ture oi about 40 toabout 120 0., the relative air was introduced as requiredwhil' cooliorder to keep the temperature in th'dneighb hood of 100 C. When themixture was in 'equilibrium, 13 litres per hour of2:5-dimethyltetrahydrofurane were introdu ed -4.5 'cubic meters of airperho were also delivered to the mixture while a blow off; was made toexpelnitrogen wfi v cubicgneters of; nitrogen and 100 litres-of oxygenper hour). q BQO- litresoi oxygenwrethus';ab-' sorbed and; 13 litres ofmixturewithdrawniper hour; said a mixture 1 containing, dissolved in dimethyltetrahydrofurane, 3 kg; 7 of hexanolone-2 5 and 13kg, ofdimethyltetrahydrofurane-peroxide' which might be treated as above setforth,--for I conversioninto ketolv o ro s applieablenot only to methylderivatives-'0; tetrahydrofurane "but alsoto its; ethyl, propyl,isopropyl and like derivatives. ;It'is also possibletouseas-a startingmaterial a'tetrahydrofuranle -compound havingone or more aromatic nucleias substituents.

ltis-within-the scope of our-inventionto workat a subatmdspheri-orsuperatmospheric -pressure.

What we-claim is: ,7 I

l. A process for preparinga v-hydroxyoxo;ali-- phatic compound, whichcomprises --oxidizing; =a; tetrahydrofurane compound of;the classconsisting of tetrahydrofurane and alkyl substituted;tetrahydrofuranesat a temperature-of about to about-120 C; so as toproduce -a :mixture compro 'or'tions of said tetrahydrofurane compound,peroxide and" aliphatic compound being those which arein equilibrium atsaid temperature; continuously supplying a gas that contains oxygen andfurther amounts of said; tetrahydrofurar'ie compoundato said body,:intheme'quired relative proportion ,f or conversion.of-thetetrahydrofurane compound thus supplied 'to 'the correspondingperoxide;v continuously withdrawingliquid from A said body; and.separatingzsaid"y-hydroxy oxo" compound from theliquid'thus'withdrawnzt 5. The process'of claim4;wherein the'laststep."comprises distilling saidliquid to remove'peroxide and tetrahydrofuranecompound therefrom' and" obtain said aliphatic compound;

6. A process for preparingafry-hydroxyoxo aliphatic compound; whichcomprises" heatiny'a 1 mixture of Water andaperoxide'oftheclass'consisting of. tetrahydrofurane peroxide andalkyl' substitutedtetrahydrofurane peroxides, at a tem perature of about 40 to about 120Cgsaid mix= ture having a pH-value other than'7,'so"as toob-f tain amixturecomprising waterand the'y-hyf droxy-oxo aliphatic compoundcorrespondingm f prisin the peroxide of saiidttrahyfdfoturane compound,-a 'y-hydroxy-oxo aliphatic-compound which" is the decomposition productof -the same peroxidejand'ur'ic'orivrted tetrahyjdro iurane compoundfand isolating said Y-hydroxy-oxoali-'phatidconipound'froifi'saidmixture; n 2." A process for preparing-ay-hyfdroxyi oxo 'aliv pha'ti'cf compound; which-comprises oxidiqtetiahydfofurafie' 'compoiirid of the class con ing of'te'trahydrofurane and alkylsubst1tuted tetrahydrofurans in admixturewit afsr nall pro pcrucn of anoxidauon batalyst'selected gro n the groupconsistingof "salts" of mang'anefsek-cobalt and CI," sdas 'to' produce aper-snag; heating said peroxi'dtd a moderate tempratureabove 4;0 Q.;; Iso as to ob'ta'in a product comprising the dr'zsxy oxo aliphaticcompoundcorresponding -to said peroxide: and isolating "said aliphaticcom- 65 pdund' froiri'said roduct.

a temperature of'ab'out to about ip" said peroxide; andisolatingsaidaliphatic com pound from the last named mixture.

'7. A process for preparing a""y hydroxy=oxo aliphatic c0mpo'und,which'comprises boiling"a" dilute'acidsolutionofa peroxideoftlfe'iclass'cosisting of rtetrahydrofurane peroxideand""alkyl substitutedtetrahydrofurane peroxides, so"as'"to"" obtain an' aqueous 'solution'of*y-hydroxy-oxo an: phatic 'compound' corresponding 'tosaidpeiox de'j'and isolating said aliphatic compound from the last named solution:MAURICEMAINQQNY PIERRE 'CHASSAI N GF'."

REFERENCESbI T'ED 9 5 The following referencesar'e bf-"metatime me orthismt V v UNiTED- STATES PATENTS

